Connecticut · R.C.S.A. §19-13-B103
Septic system requirements in Connecticut
Tank sizes, drainfield rules, setbacks, permits, and real costs — pulled from Connecticut's own code rather than a national average.
- 3-bedroom tank
- 1,000 gal
- Design flow
- 150 gpd/BR
- Typical install
- $14,000–$35,000
- Permit fee
- $250–$900
- Well setback
- 75 ft
- Permitted by
- County / local
Septic tank sizes required in Connecticut
Connecticut sizes systems on a design flow of 150 gallons per day per bedroom. The tank must meet both the bedroom table below and a 2× daily-flow detention requirement — whichever produces the larger number governs.
| Bedrooms | Design flow | Code minimum | Recommended |
|---|---|---|---|
| 1 bedroom | 150 gpd | 1,000 gal | 1,000 gal |
| 2 bedrooms | 300 gpd | 1,000 gal | 1,000 gal |
| 3 bedrooms | 450 gpd | 1,000 gal | 1,000 gal |
| 4 bedrooms | 600 gpd | 1,250 gal | 1,250 gal |
| 5 bedrooms | 750 gpd | 1,500 gal | 1,500 gal |
| 6 bedrooms | 900 gpd | 1,750 gal | 2,000 gal |
Source: R.C.S.A. §19-13-B103. The recommended column rounds the governing requirement up to a tank size manufacturers actually stock.Run your own numbers →
Drainfield size and cost by soil type
For a three-bedroom home in Connecticut at 450 gpd. This single table explains most of the variation between quotes — the area scales inversely with how fast your soil accepts water, and the drainfield is the largest line item in the job.
| Soil | Loading rate | Absorption area | With reserve | Typical total install |
|---|---|---|---|---|
| Medium sand | 0.8 gpd/ft² | 563 ft² | 1,126 ft² | $12,900 |
| Sandy loam | 0.5 gpd/ft² | 900 ft² | 1,800 ft² | $16,300 |
| Loam | 0.4 gpd/ft² | 1,125 ft² | 2,250 ft² | $18,600 |
| Silt loam | 0.3 gpd/ft² | 1,500 ft² | 3,000 ft² | $22,400 |
| Clay loam | 0.2 gpd/ft² | 2,250 ft² | 4,500 ft² | $30,100 |
Estimates use Connecticut's cost index of 1.13× the national average. Build a line-item estimate →
Permits and who issues them
Local health departments and districts permit systems under 5,000 gpd using the state Public Health Code and DPH Technical Standards; DPH handles larger systems.
| Permit required | Yes |
|---|---|
| Typical fee | $250 – $900 |
| Soil evaluation | Required before permit |
| Licensed installer | Required |
| Turnaround | 3–8 weeks |
| Ongoing inspection | Not mandated statewide |
| Reserve area | 100% replacement area required |
Minimum setback distances
Measured horizontally from the drainfield unless noted. Local rules are frequently stricter, and on a small lot these numbers — not the soil — often decide the layout.
| Private water well | 75 ft |
|---|---|
| Property line | 10 ft |
| Surface water | 50 ft |
| Building foundation | 25 ft |
Regulatory contact
Connecticut Department of Public Health — Environmental Engineering
portal.ct.gov · 860-509-7296
What makes septic hard in Connecticut
Glacial till over shallow bedrock across most of the state means ledge is a routine excavation cost, not an exception.
Small lot sizes in older neighbourhoods often leave no room for the required reserve area, which is what turns a repair into a full redesign.
Seasonal high water tables in the Connecticut River valley restrict trench depth.
Things that catch people out
- The binding document is the DPH Technical Standards, not the Public Health Code section itself. The standards are revised more often than the code.
- The reserve area must be shown and protected on the plan — building a shed or pool on it is a common and expensive mistake.
Bedroom-by-bedroom tank capacities come from the DPH Technical Standards tables; confirm the current edition with your local health district.
Connecticut septic questions
What size septic tank do I need in Connecticut?
A three-bedroom home in Connecticut requires a minimum 1,000 gallon tank under R.C.S.A. §19-13-B103. Design flow is 150 gallons per day per bedroom, and the tank must also hold 2 times daily flow, so the practical recommendation is 1,000 gallons.
Do I need a permit for a septic system in Connecticut?
Yes. Local health departments and districts permit systems under 5,000 gpd using the state Public Health Code and DPH Technical Standards; DPH handles larger systems. Fees typically run $250 to $900, with a turnaround of about 3–8 weeks. A soil evaluation or percolation test is required before a permit is issued.
How much does a septic system cost in Connecticut?
A conventional system for a three-bedroom home typically runs $14,000 to $35,000 installed. Soil quality moves this more than anything else — on tight clay requiring a mound, budget two to three times the low end.
How far must a Connecticut drainfield be from a well?
75 feet from a private water well. Local rules can be stricter.
Sources
Every figure on this page traces to one of these documents.
- R.C.S.A. §19-13-B103 — On-site Sewage Disposal Systems · verified 2026-09-18
- CT DPH Technical Standards (2024) — Technical Standards for Subsurface Sewage Disposal Systems · verified 2026-09-18